1. Technical Field
The present invention relates to novel microorganism Rhizobium sp. KB10 having properties of promoting growth of Botryococcus braunii and increasing fatty acid content including oleate.
2. Description of the Related Art
Biodiesel from a raw material like plant oil like corn oil, rapeseed oil, and palm oil is a representative example of biodiesels that have been already commercially available and it is produced in rapidly increasing amount all over the world. However, due to the problems associated with high price of raw crops and relative cost increase caused by additional cost, or the like, its competitiveness is relatively weak compared to diesels derived from crude oil. In addition, recent price increase of raw crops poses new problem for competitiveness of the biodiesel. Examples of main supply source for biodiesel include phothosynthetic oil like plant oils and fats and algae oils. However, since the broader use of biodiesel having photosynthetic oils as a source may cause insufficient food supply or a new environmental problem relating to mass cultivation of raw crops, there has been a need for new supply source in another form.
Recently, as an energy source for stable and economically favorable production of biodiesel, algae are getting an attention. Algae are either photoautotrophs or photoheterotrophs and have a characteristic of growing in any place as long as solar energy, water, and carbon dioxide are available. They also have advantages that, compared to corn, palm, or sugar cane as a conventional plant raw material, the productivity is higher and also content of fats as a material for producing biodiesel is significantly higher than other supply sources. Algae can produce not only oils but also various useful substances, and they also have advantages as a renewable energy source as they are not conventional food crops. In case of microalgae belonging to algae, biodiesel production per unit area is about 58,700 L/ha, which is 130 times higher than soy bean (446 L/ha), when calculation is made for a standard case in which oil content is 30% (Chisti. Biotechnology Advances, 2007, vol. 25, p 294-306). Thus, it can be said that the mass culture of microalgae is a green technology which can prevent global warming by absorbing carbon dioxide present in atmospheric air and it enables biodiesel production from algae as seedlings.
Due to increasing focus from all over the world on production of biofuels by using algae, big national-level investments as well as related studies are being made. There is a representative international company like SOLIX, GreenFuel, Cyannotech, and the like. In Korea, the government leads many investments on basic research and industrialization.
Among microalgae, Botryococcus braunii is cluster type microalgae widely present in fresh water, salt lake, and warm climate or tropical regions. Cellular oil content is as high as 75%, which is much higher than other algae that are known so far, and the lipids produced by them can be easily transformed into biodiesel. However, the biggest problem in production of biodiesel using Botryococcus braunii is that the growth is slow (i.e., only two times in 6 days), and due to low growth rate, they can be easily contaminated with other microorganisms when they are cultured in large scale in outside environment.
Meanwhile, a method for producing fatty acid alkyl esters by using microorganism having oil-producing property is disclosed in Korean Patent Application Laid-Open No. 2011-0007989, a method for extracting hydrocarbons from microalgae is disclosed in Korean Patent Application Laid-Open No. 2000-0000842, and a method for producing hydroxyalkanoate alkyl ester by using microorganism having polyhydroxy alkanoate-producing property is disclosed in Korean Patent Application Laid-Open No. 2011-0002951. However, novel microorganism Rhizobium sp. KB10 having properties of promoting growth of Botryococcus braunii strain and increasing oleate content as disclosed in the present invention has not been described in any literatures at all.